The gradient of the line joining the points P(2, -8) and Q(1, y) is -4. Find the value of y
A
2
B
4
C
-4
D
-3
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
P(2, -8) and Q(1, y)
Gradient of slope(m) = \(\frac{y_2 - y_1}{x_2 - x_1}\)
- 4 = \(\frac{y - (-8))}{1 - 2}\)
-4 = \(\frac{y + 8}{- 1}\)
cross multiplying
4 = y + 8
y = 4 - 8 = -4
Source: Myschool Past Questions Archive (Record #71829)